Most construction projects on existing homes work out fine, but there can be problems. This is why plans and specifications are useful – because they enable all the people involved to spot potential issues and agree a solution before work starts.
- Thin black lines up and down or across walls and ceilings.
This is where cold air is coming from behind plasterboard and reaching the top finish coat. Warm moist air inside your rooms is creating 'pencil line' mould. There may not be sufficient insulation, and the air tightness in the area behind the wall or ceiling may be poor (which means that air is leaking out).
How to avoid: When planning new work, discuss insulation and the proposed quality of work, especially in tight areas that are hard to reach.
- Patches of black mould on walls and in corners.
This could be 'cold-bridging' where an uninsulated construction detail is in contact with an inside surface. Steel beams, pipes and even timber can do this.
How to avoid: When planning new work make sure that anything that can conduct cold doesn’t extend into the house without a thermal break (insulation) being added.
- Recurring cracks in plaster.
You normally get some small cracks in new plaster and decorated finishes as new building work dries and 'settles'. But recurring cracks every summer and winter are usually the sign of repeated movement. A common cause is ground movement caused by summer drying shrinking the ground which then swells again when the ground water returns. This can be caused by trees too close to the building (and also by removing trees) and can be quite severe on clay soil.
How to avoid: Well-engineered foundations suited to your home’s ground help to prevent this.
- Bumps or cracks appearing in a floor.
This is usually a sign of movement in the ground beneath a concrete floor slab or excessive joist movement in a timber floor.
How to avoid: If your property is built on a clay soil or on a filled site you’ll need to reinforce the floor slab. Bouncy floor joists can often be cured simply by fixing pieces of wood called noggins between them, or by adding additional support.
This is a common problem in conservatories or garden rooms with polycarbonate or glass roofs. It is worse if your room faces south or west.
How to avoid: Ventilation and roof blinds might help with overheating but ultimately the only real solution is a solid insulated roof. Don’t be tempted to take the door off between the conservatory and the rest of the house – this thermal separation is really important because it stops your other room overheating or becoming colder in winter, and is often a legal requirement.
- Noise transfer.
There is actually a lot you can do to reduce problems with noise in or between houses. You might want to avoid hearing the TV in an adjacent room or muffled footsteps on the stairs.
How to avoid: Older terraced or semi-detached houses didn’t legally need any sound insulation when they were built so you might want to invest in acoustic updates as part of a bigger refurbishment project.
- Smoke alarms going off when you burn the toast.
Generally caused by lack of ventilation (you should install and use a powerful extractor fan or cooker hood that vents to outside if you are planning a new kitchen). Smoke alarms are often poorly sited and not maintained.
How to avoid: Make sure you use the right type: some detect a rapid rise in heat so are ideal in a kitchen and others detect smoke so are best in circulation areas. Consider fitting linked mains powered alarms throughout your home if you are planning a refurbishment.
- Gurgling pipes in the bathroom and unpleasant smells.
If you have long drainage runs the water rushing through the pipe can 'pull' or syphon the water out of the trap or u-bend if you have the wrong type fitted.
How to avoid: Drainage runs need to be ventilated and have water traps that stop smells coming into the house from the sewer.
- Rainwater leaks.
These commonly occur around windows, doors, balconies and chimneys if they have been installed incorrectly
How to avoid: Include cavity trays, damp proof courses or lead flashings in your plans. Blocked or loose guttering and downpipes are also often the culprit and need regular maintenance. You should arrange regular visual checks of your roof covering, chimneys and pipework.
- Bulbs blowing and fuses or circuits tripping. These are usually caused by overloaded circuits, faulty appliances or fittings, or problems with the wiring and earthing.
How to avoid: Always have electrical checks and work carried out by a properly qualified and certified electrician.